Showcasing the concept of light-induced homo¬lysis for the generation of radicals, the CuII-photocatalyzed decarboxylative oxygenation of carboxylic acids with molecular oxygen as the terminal oxidant is described. Two CuII-carboxylate complexes...
Over the past decade, photocatalysis has developed as a powerful strategy for the selective functionalization of molecules through radical intermediates. Besides the well-established iridium- or ruthenium-based photocatalysts, which ideally fulfill...
We report the visible light-mediated coppercatalyzed vicinal difunctionalization of olefins utilizing bromonitroalkanes as ATRA reagents. This protocol is characterized by high yields and fast reaction times under environmentally benign reaction conditions with exceptional scope, allowing the rapid functionalization of both activated and unactivated olefins. Moreover, late-stage functionnalization of biologically active molecules and upscaling to gram quantities is demonstrated, which offers manifold possibilities for further transformations, e.g. access to nitro-and aminocyclopropanes. Besides the synthetic utility of the title transformation, this study undergirds the exclusive role of copper in photoredox catalysis showing its ability to stabilize and interact with radical intermediates in its coordination sphere. EPR studies suggest that such interactions can even outperform a highly favorable cyclization of transient to persistent radicals contrasting iridium-based photocatalysts.
A series of copper complexes was synthesized and studied as photocatalysts for the chlorosulfonylation of olefins. Featuring a tetradentate ligand consisting of one amino quinoline and two methyl pyridine moieties, the resulting Cu(II)‐complex is effective under visible light irradiation to add sulfonyl chlorides to alkenes and alkynes, including unactivated aliphatic olefins. A weak base additive such as Na2CO3 prevents catalyst poisoning, resulting in an improvement of reaction yields and catalyst lifetime. A broad scope of sulfonyl chlorides and alkenes/alkynes as coupling partners are amenable for the title process, including examples previously reported unsuccessful with established copper‐based photocatalysts.
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